Preparing for Analyzing and Visualizing Data with Power BI (Microsoft Exam 70-778) – Part 1

Recently I have successfully passed “Analyzing and Visualizing Data with Microsoft Power BI” (Microsoft Exam 70-778). After working some time now with Power BI (and for sure Excel), I want to “officially confirm” my knowledge aiming for Microsoft’s MCSA “BI Reporting” certification. This exam was the first step. Maybe it is also some time ago, since you took a “formal” exam, as it was the case for me. That’s why I am sharing my experience preparing for this one in a 2-part blog post. Both posts assume you have already working knowledge with Power BI. If not, I have some recommendations where to go at the very end of my second post.

No exam questions here

Just before actually taking the exam you need to agree to Microsoft’s exam policies which include a non-disclosure agreement. Consequently, I can’t and won’t share any exam questions here.

A few more words on that: Searching the internet for preparation materials you will also find offers where you can buy so called “braindumps” of exam questions. Call me boring, but personally I think that if you really want to demonstrate your skills and not only show off with a badge or a certification, it’s better to invest some time and study to pass.

The book did a very good job for me: It does not – and also does not want to – serve as a complete reference for all the knowledge required to pass the exam. Rather it served me as an overall guide through the topics covered by the exam, as well as pointing to further resources. Anyway, as the pace of new features added to Power BI is quite fast, naturally any printed resource has its limitations as it can only represent the status quo at the time when it has been published. Out of and on top of the resources mentioned in Daniil’s book here are my favorite ones listed by the skills measured in Exam 70-778.

Of course this is all about Power Query and the “M” data transformation language. Even assuming that you are already familiar with syntax, structure and (some of) the language’s formulas, I can warmly recommend to revise the official Power Query “M” reference. It’s not about studying this extensive body of knowledge line by line, it’s about

Looking up subtle details of common formulas you already know

Getting an overview of formulas which you might have not yet used at all

Here a personal tip on studying practice: I like to use post-it notes. They are not only useful for revising study notes at a later point in time. For me, just the simple act of writing it down makes it easier to remember. Hence, I ended up with my desk nearly fully covered by small yellow papers.

Beside that, I can also recommend to have a closer look to Gil Raviv’s excellent blog with a lot of useful content – not only but especially – related to Power Query.

Modeling and Visualizing Data

Modeling Data (Power Pivot, DAX language):

For a general overview/ revision of the topic I personally found a video done by Kasper De Jonge, which again in general provides very good Power BI content in his blog, super valuable:

Other than that it’s important that you have a good grip on data modeling basics e.g. star scheme, relationship types (single-, bi-directional) and cardinalities of relationships (1:1, 1:N, “Many to Many”). Again, there are lot of useful resources out there. I can recommend to check out for example Ruth Pozuelo Martinez’ content on curbal.com and Curbal’s Youtube channel with e.g. this video in particular regarding data modeling best practices:

In the second part of this post, I will…

point you to the maybe most comprehensive and valuable resources regarding Power BI Data Modeling in general and the DAX language in particular

tackle the third skill measured by exam 70-778 i.e. “Configure Dashboards, Reports and Apps in the Power BI Service” with respective resources

give you some general advice when taking the exam

also provide some materials for folks just starting out with Power BI or are quite new to the product